[Benchmark]
[Arguments("Hello World!")]
public int CharToUpperInvariant(string args)
{
    int accum = 0;
    for (int i = 0; i < args.Length; i++)
    {
        accum += char.ToUpperInvariant(args[i]);
    }
    return accum;
}

[Benchmark]
[Arguments("Hello World!")]
public int CharToLowerInvariant(string args)
{
    int accum = 0;
    for (int i = 0; i < args.Length; i++)
    {
        accum += char.ToLowerInvariant(args[i]);
    }
    return accum;
}